1. Field of the Invention
The device of the present invention relates to a new and improved timing device for reciprocating pumps.
2. Description of the Prior Art
Known pump timer combinations typically utilize the power fluid as opposed to ambient fluid as the timing medium. Other prior art timing devices include an electrical magnetic coil to arm or reset the timer and provide output through an electrical contact. Disadvantages of these prior art devices include a need for electric power, with attendant hazards when used in explosive atmospheres, structural complexity and susceptibility to break down due to contamination of electrical components, and particularly fluid flow circuits.
Typical timing devices are illustrated, for example, in U.S. Pat. No. 3,012,541. This device employs an external electrical signal to actuate time delayed operation. Another apparatus disclosed in U.S. Pat. No. 3,160,486 employs a timer that is sealed by o-rings that is subject to substantial wear resulting in undesirable down time for repair. In addition, the system disclosed in this patent employs four timing compartments and an accumulator vessel greatly increasing the complexity of the timer and the probability of break down. The system of the '486 patent also includes several orifices through which the media must flow resulting in change in operating characteristics due to orifice contamination and further increasing the likelihood of down time for servicing.